Cu incorporation efficiency to the ZnO lattice in nanoparticles synthesized by an aqueous solution method A. Iribarren,*, E. Hernández-Rodríguez Instituto de Ciencia y Tecnología de Materiales, Universidad de La Habana, Zapata y G, Vedado, Plaza, La Habana 10400, Cuba. *Corresponding autor. E-mail: firstname.lastname@example.org, email@example.com ZnO and Cu-doped ZnO nanoparticles were obtained by chemical synthesis in aqueous media. Structural analysis gave the dominant presence of wurtzite ZnO phase forming a solid solution Zn1-xCuxO. For high Cu doping CuO phase is also present. The diffraction peaks are shifted either right or left respect the ZnO powder pattern according to the Cu concentration, which indicates changes in the lattice size. For low Cu concentration the lattice shrinks due to Cu atoms substitute Zn atoms. For high Cu concentration the lattice enlarges due to predominance of interstitial Cu. From elemental analysis we determined and analyzed the incorporation efficiency of Cu atoms in Zn1-xCuxO as a function of the Cu concentration in the precursor dissolution. Combining structural and chemical results we described the Cu/Zn precursor concentrations rw in which the solid solution of Cu in ZnO is predominant. In the region located at rw > 0.2–0.3 it is no longer valid. For Cu/Zn precursor concentration rw > 0.3 interstitial Cu dominates, and some amount of copper oxide appears. The effective size of nanoparticles decreases as the Cu concentration increases.